Timing device for cooking meat

ABSTRACT

An alarm type timing device is provided for use in cooking meat. The device includes a non-linear, electronic circuit adapted to approximate the unusual nature of outdoor charcoal-grill type of cookery. The circuit is so designed as to act as a mathematical model for the meat being cooked and, using empirical data, takes into consideration the nature of the bed of charcoal, the desired &#39;&#39;&#39;&#39;doneness&#39;&#39;&#39;&#39;, and the thickness of the meat, and thereby provides an alarm signal when the cooking is completed.

O United States Patent 1 91 [111 3,732,468 Witt et al. 1 1 May 8, 1973[54] TIMING DEVICE FOR COOKING [56] References Cited MEAT UNITED STATESPATENTS [75] Inventors: W weapon; George 3,106,667 10/1963 Winchel ..317141 5 Suhm, Brldgepofi, both of Com 3,582,716 6/1971 Traina ..3l7/148.5B [73] Assignee: Food Automation-Service Techniques, Inc., Bridgeport,Conn. S y HIX ssistant Examiner-Harry E. Moose, Jr. [22] Flled 1972Attorney-Roland T. Bryan et al. [21] Appl. N0.: 226,741

[57] ABSTRACT RltdU.S.A 1' t D ta ea 8 pp [ca a An alarm typetimingdevice is provided for use in [63] Continuation-impart of Ser. No.111,426, Feb. 1, cooking meat. The device includes a non-linear, elec-1971, abandoned. tron'ic circuit adapted to approximate the unusualnature of outdoor charcoal-grill type of cookery. The [52] US. Cl...307/l49, 99/344, 317/141 S circuit is so designed as to act as amathematical 51 1m. (:1. ..G07c 1/02 model for the meat being cookedusing empirical [58] Field of Search ..99/342, 344; data, takes intoConsideration the nature of the bed of charcoal, the desired doneness",and the thickness of the meat, and thereby provides an alarm signal whenthe cooking is completed.

7 Claims, 13 Drawing Figures PATENTED M Y 8 ms SHEET 1 BF 3 TIMINGDEVICE FOR COOKING NIEAT This application is a continuation-in-part ofapplication Ser. No. 111,426, filed Feb. 1, 1971, entitled TimingCircuit for a Timer Alann, now abandoned.

BACKGROUND Meat cooking timers, such as timers used for outdoor cookeryof steak over charcoal, normally are simple clock-type timers which canbe set to give an alarm at the end of a predetermined time. Some meattimers, on the other hand, utilize a probe inserted in the meat tomeasure internal temperatures and so determined degree of cooking.Neither technique is too useful, however, when the cooking is done overa charcoal grill.

The inventors have found that the time that it takes a steak to cookover charcoal, for a given degree of doneness, such as rare or welldone, does not relate directly to the thickness of the steak. That is,it has been found that if one steak is, say, 50 percent thicker than ananother one, the thicker steak will have to be cooked more than 50percent longer than the thinner one in order to obtain the same degreeof doneness. As a result, one cannot determine the desired length oftime for a given degree of doneness by measuring the thickness of thesteak. 7

The above information has been determined empirically. The theoreticalreason why this is true is not know, but it may be that the steaksreceive the heat from the fire and re-radiate it. This re-radiationincreases when the outer surfaces get hotter, and the result is that thecooking time goes up at a very fast rate as steaks get thicker.

By way of illustration, a 1 '6 inch steak might take 6 minutes to reacha desired degree of doneness; but a 2 inch steak would take twice thatlong to reach the same degree of doneness, even though the 2 inch steakis only a third thicker and one would assume should take a third moretime. This means that the cooking time for a steak rises rapidly as thesteak gets thicker, and cooking time cannot be calculated on a linearbasis.

This application is a continuation-in-part application of applicationSer. No. l 1 1,426, filed Feb. 1, 1971.

SUMMARY OF THE INVENTION We have discovered that meat cooked over anoutdoor grill, such as a broiled steak, has unusual characteristicsrelating to its cooking times. Three factors are of prime considerationin determining the cooking time:

a. the quantity of hot coals and their distance from the meat;

b. the degree of doneness of the meat desired, such as medium rare; and

c. the thickness of the neat.

Normally most people regularly use the same grill and substantially thesame number of coals, so that the first factor is standardized. Theextent of cooking of a given piece of meat may vary, however, from timeto time in accordance with the particular persons desires. And, ofcourse, the thickness often varies.

Under these circumstances we have found that a standardized base time ofcooking is required, together with a variable time which depends uponthe thickness of the meat and the desired degree of doneness. Thevariable time requires introduction of non-linearity into the timerscontrols. We have done this in such a manner as to match thecharacteristics of the meat.

We have provided a timing circuit which, when turned on, provides a basetime period plus an additional time period which relates to the degreeof doneness desired and the thickness of the meat. The unit uses thecharging curve of a capacitor to determine the time cycle and varies therate of charging in accordance with the above factors. When thecapacitor is fully charged it opens a first gate, preferably aunijunction transistor for precise control of tolerances, which in turnfires an SCR. The SCR can control a suitable alarm system such as alight or oscillatory circuit.

THE DRAWINGS FIG. 1 is a perspective view showing a typical outdoorgrill with hot coals being used to cook some steaks.

FIG. 2 is a perspective view of the timing device of our invention.

FIG. 3 is a typical curve showing cooking time variations with thicknessof steak, to exemplify part of our discovery.

FIG. 4 is a typical curve showing degree of doneness versus cookingtime.

FIGS. 5, 6, 7 and 8 show the results as we varied the thickness of thesteak and determined how long we would have to cook it. They show thecooking times for rare, medium rare, medium and well done, respectively.The shaded area shows the general range of cooking times, while thedotted line in the curves shows the degree to which our device has beenable to approximate those times.

FIGS. 9, 10, 11 and 12 show the degree of doneness varies with time.These are for steaks that are 5 4 inch, 1 inch, 1 A inch and 2 inchthick, respectively. As with the earlier figures, the shaded areaindicates the range of cooking times as determined empirically, and thedotted line shows the actual times produced by our device for thesettings in question.

FIG. 13 is a schematic diagram showing the circuitry of our invention.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 of the drawings ispresented to show, in broad outline, the use of the invention. Itillustrates an outdoor cooking unit 1 with hot coals 2, a grill 3, andsteaks 4 being cooked. The timing device of our invention 5 is shownpositioned over to one side on top of the unit.

FIG. 2 is a closeup perspective view of the timer substantially as it iscurrently being marketed. The timer includes an ON switch 7, a rotatabledoneness control 8, a rotatable thickness control 9, and a small grillor opening 10 to emit the alarm signal when cooking is done. Associatedwith the two timing controls 8 and 9 are scales 12 and 13. Scale 12 hascontrol positions marked on it showing the positions that control 8should be set at for determining the degree of doneness. Scale 13 showsthe position that control 9 should be set to adjust the cooking time forthe thickness of the steak. The positions of the indications on controls12 and 13 serve to control the linearity or non-linearity of thevariation of times with doneness and thickness.

FIGS. 3 and 4 are exemplary of the discoveries which we made relating tocooking times. FIG. 3 is a graph showing how the cooking time for agiven degree of doneness will vary as the steak increases in thickness.Going from left to right the length of time increases, and going frombottom to top the thickness of the steak increases. As can be seen, forthinner steaks the length of cooking time appears to be in direct ratioto the thickness of the meat and so is linear. However, the curvesuddenly bends over to the right showing a sharp elbow, after which thecooking time increases rapidly as the thickness of the steak increasesonly slightly. We find that this begins to take place at about a 1 inchsteak. Though we do not known the actual explanation, as mentionedabove, it would appear to be due to the fact that after the meat reachesa certain thickness less radiant heat is able to penetrate the meat andthe central part of very thick steaks must be cooked by conducting heatfrom the outside.

FIG. 4 is a similar exemplary graph, this time to show how the degree ofdoneness varies with time. Once again time increases as one goes fromleft to right; doneness increases from bottom to top. Though it couldwell be argued that our definitions of rare, medium rare, medium andwell done are different from those of other people, we have found thatthere is generally a directly proportionate ratio, and so the curve onthe graph is a straight line. Regardless, if other people have differentconceptions of the degree of doneness than we have, they could use thetimer by simply setting it slightly difierently than is shown on thedial itself. This would also enable them to compensate for thedifference between the intensity of the heat from their fire and thedistance of the meat from their fire, as contrasted with what we feltwas standard in our work. Knowing the theoretical times and variationsof them for cooking steak gave us a basis upon which we were able toinvent the present timer and have it operate accurately.

FIGS. 5, 6, 7 and 8 show further results of our empirical work. Eachshow what we discovered to be the proper cooking times as thickness ofthe steak varies. We assume, in each instance, use of the same cookingheat. The figures show, respectively, times for rare, medium rare,medium, and well done cooking. The shaded area in the figures shows thevariation in cooking time we experienced for various pieces of meat. Thedotted lines show the actual times that our unit will provide when setfor a particular thickness and degree of doneness.

It will be noted that the dotted lines all fall within the shaded areas,and so should provide satisfactory cooking times. The only exception tothis is that the dotted lines tend to get outside the shaded area forthe thicker steaks. This is deliberate, based on the possibility thatperhaps not quite so much time as we though necessary was required forthe very thicksteaks. In the particular instance here, it simplyrepresents the design criteria we applied to our scale setting indiciaand could be varied, as desired, by simply adjusting the positioning ofthe indicia for the 2 inch steaks differently for the scales.

Similarly, FIGS. 9, 10, 11 and 12 show the variation of doneness withtime for inch, 1 inch, 1 inch and 2 inch steaks, respectively. Again theshading shows the empirical times we found, and the dotted lines showsthe actual times provided by our timer. Once again (FIG. 12) theparticular timer scale was set so the actual time for thick steaks isslightly less than the empirical time of our results.

Turning now to the actual circuit used in our preferred embodiment (FIG.13), capacitor 22 is charged from DC supply 15 through trimming resistor23, fixed resistor 25, variable resistor 8 and variable resistor 9. Itwill be noted that variable resistors 8 and 9 correspond to the donenessand thickness controls shown in FIG. 2; this is because the doneness andthickness controls are variable resistors and matched to the scales l2and 13. Resistor 25 with trimming resistor 23, however, serves toprovide a minimum base time for charging and is related to the standardsize, fire and distance that the meat is from the fire referred toabove. Thus it can be seen that the charging time of capacitor 22 is afunction of the totality of resistors 23, 25, 8 and 9 and so the time tocharge capacitor 22 can be controlled and predetermined.

Unijunction transistor 24 is biased by a voltage divider circuit made upof resistors 32 and 34 across the DC supply 15, with the midpointbetween the resistors leading to terminal 29.

The operation of the first gating means 14 is as follows: Terminalresistor 23 is adjusted (usually in the factory) for standardizedoperation; variable resistor control 8 is adjusted to the degree ofdoneness desired; and it should be noted that the spacing of the rare,medium rare, medium, and well settings on scale 12 of timer 5 aresubstantially uniformly spaced so that a linear variation and cookingtime is accomplished by moving the doneness control plate. The steakthickness control 9 is set to the proper position on scale 13. It willbe noted that here, by contrast, the spacing of the positions forthickness on scale 13 is not linear, i.e., the positions are not spacedproportionately to the proportionate changes in thickness, but, rather,is non-linearly spaced in accordance with the teachings shown by theempirical data of FIGS. 5 through 8. Thus, scales 12 and 13 aregraduated to reflect the data we found on variations of cooking timewith thickness and doneness. This, then, serves to make our timer amathematical model of the actual cooking process.

After the settings have been made, ON-OFF switch 17 is closed to connectfirst gating means 14 across the DC supply 15. It will be noted thatswitch 17 is a gang switch, one portion of which connects the DC supplyto the first gating means circuitry and the other portion of which shortcircuits capacitor 22 to discharge it. The switch is so ganged that whenthe gating means is connected to the DC supply, the capacitor is notshort circuited, and vice versa. When these first gating means areconnected across the DC supply, current flows through resistors 23, 25,8 and 9 to charge capacitor 22. At first the voltage across the chargingcapacitor 22 is not high enough to turn on the programmable unijunctiontransistor 24, and the transistor 24 is in its normally non-conductingstate. While the ON OFF switch 12 remains closed, the charge on thecapacitor 22 continues building up, and, after a time intervaldetermined by the time constant of the series circuit of resistors 23,25, 8 and 9 and capacitor 22, the voltage across the capacitor 22reaches a value sufficient to turn on the programmable unijunctiontransistor 24 to cause it to commence conducting. Resistor 30 serves asa bleeding resistor.

When the programmable unijunction transistor 24 commences conducting,the signal at its output terminal 27 is applied to the trigger terminal33 of an SCR 36. The SCR 36 may be a Silicon Controlled Rectifier of thetype of Unitrode ID 100 or Unitrode ID 200. The terminals 27 and 33 areconnected by means of a voltage dropping resistor 38. The current signalat the trigger terminal 33 causes the normally closed SCR 36 to commenceconducting, and the conducting state of the SCR 36 allows theoscillating circuit 18 to be driven into oscillation by the voltage fromthe DC supply 15. The oscillating circuit 18 is a conventionalconfiguration of capacitors 40 and 42, resistors 44 and 46 and an NPNtransistor 48.

When the circuit 18 is oscillating, the capacitor 42 dischargesrepetitively across the transistor 48 to make the voltage drop acrossthe resistor 44 fluctuate at the oscillating frequency. The audio device20 which is connected across the resistor 44 is thus caused to generatean audio signal. The audio device 20 may be a piezoelectric device suchas a Clevite PXT Unimorph, or it may be another suitable device forgenerating an audio signal in response to an oscillating voltage input.

The audio signal is terminated by opening the ON- OFF switch 17. Ableeding switch 50 is mechanically ganged with the ON-OFF switch 12 tobe in a complementary state therewith, i.e., to be open when the ON- OFFswitch 12 closes, and to close when the ON-OFF switch 12 is open so asto discharge the capacitor 22. The SCR 36 is protected against firing bysurges, occurring when switch 50 is closed, by series capacitor 35 andresistor 37 leading from the SCR gate to Ground.

In operation of the timing circuit of FIG. 13, and after the desiredtime interval has been selected by controls 8 and 9, the selectedinterval commences with the closing of the ON-OFF switch 12. When thecharge on the capacitor 22 reaches a predetermined value, determined bythe bias on terminal 29 of programmable unijunction transistor 24 bymeans of the voltage divider made up by resistors 32 and 34 across DCsupply 15, the programmed unijunction transistor 24 commences conductingand turns on the SCR 36. When the SCR 36 commences conducting, theoscillating circuit 18 begins oscillating and drives the audio device 20to generate an audible signal to indicate that the predetermined timeinterval has elapsed. This means that one side of the steak is done. Thesteak is then turned over and the process repeated. Desired timeintervals for this mean time may be chosen by suitably choosing andsetting the appropriate components of the FIG. 13 circuit. We have foundthat the following components provide appropriate timing to correspondwith the desired empirical times:

Resistors Transistors 25 580K ohm U l 3T1 Unijunction IX ohm 36 lDlOOSCR 32 22K ohm 48 2N2222 34 27K ohm 37 10K ohm Capacitors 38 10K ohm 391.514 ohm 22 150 mfd 44 47K ohm 0.01 mfg 46 1K ohm 40 42 0.2 mfdControls Audio Device 8 & 9 2.5 megohm 20 PIN 60708 Unimorph 23 250K ohmtrimmer What is claimed:

1. A timing alarm adapted to be used for over-thegrill cooking of meatssuch as steaks, where the quantity of coals or other heat source and thedistance there from the meat is substantially constant from one cookingtime to another, but the thickness of said meat and the desired donenessmay vary, including a circuit with a first gating section and a seriallyrelated alarm section, said alarm section being controlled by said firstgating section,

a power supply therefor,

said first gating section including a timing circuit actuating the gatethereof,

said timing circuit including an RC circuit having at least one fixedresistor to provide a base time and a plurality of variable resistors toprovide variable times,

a scale associated with each said variable resistor and calibrated inaccordance with an empirically determined cooking time variable, and

an ON switch between said power supply and said first gating means forstarting said timing cycle,

whereby said timing circuit may be adjusted for a proper timing alarmfor each type of meat cooked.

2. A timing alarm as set forth in claim 1 in which one of said variableresistors is to set the timing for the degree of doneness desired andsaid associated scale is substantially linear, and another of saidvariable resistors is to set timing for the thickness of the meat beingcooked and said associated scale is non-linear.

3. A timing alarm as set forth in claim 1 in which the gate means insaid first gating section is a programmable unijunction transistor andthere is a second gating section between said first gating section andsaid alarm section having an SCR gate.

4. A timing alarm as set forth in claim 1 including means ganged withsaid ON switch for discharging said capacitor when said ON switch isopen.

5. A steak-cooking alarm timer having therein parameters related to thelinear and non-linear variables such as those occurring due to steakthickness and desired degree of doneness, and having circuitry adaptedto adjust timing accordingly, said timer including an alarm,

a control circuit for actuating said alarm capable of providing varyingcooking times,

a power supply for said control circuit,

said control circuit including a timing circuit adapted to provide afixed base time period and an additional variable time period prior toactuating said alarm,

a plurality of controls for said variable time period portion of saidtiming circuit corresponding to said variable in steak-cooking time andcorresponding to said parameters, at least one of said controls varyingon a nonlinear basis,

whereby said alarm time will vary in accordance with required cookingtime.

6. A steak-cooking alarm timer as set forth in claim 5 and having scalesassociated with said controls, said scales being marked to accord withthe desired respective said parameters.

7. A steak-cooking alarm timer as set forth in claim 6 in which saidcontrols are variable resistors in an RC circuit, and said scales aremarked corresponding to required cooking times for steak thickness anddegree of doneness.

1. A timing alarm adapted to be used for over-the-grill cooking of meatssuch as steaks, where the quantity of coals or other heat source and thedistance there from the meat is substantially constant from one cookingtime to another, but the thickness of said meat and the desired donenessmay vary, including a circuit with a first gating section and a seriallyrelated alarm section, said alarm section being controlled by said firstgating section, a power supply therefor, said first gating sectionincluding a timing circuit actuating the gate thereof, said timingcircuit including an RC circuit having at least one fixed resistor toprovide a base time and a plurality of variable resistors to providevariable times, a scale associated with each said variable resistor andcalibrated in accordance with an empirically determined cooking timevariable, and an ON switch between said power supply and said firstgating means for starting said timing cycle, whereby said timing circuitmay be adjusted for a proper timing alarm for each type of meat cooked.2. A timing alarm as set forth in claim 1 in which one of said variableresistors is to set the timing for the degree of doneness desired andsaid associated scale is substantially linear, and another of saidvariable resistors is to set timing for the thickness of the meat beingcooked and said associated scale is non-linear.
 3. A timing alarm as setforth in claim 1 in which the gate means in said first gating section isa programmable unijunction transistor and there is a second gatingsection between said first gating section and said alarm section havingan SCR gate.
 4. A timing alarm as set forth in claim 1 including meansganged with said ON switch for discharging said capacitor when said ONswitch is open.
 5. A steak-cooking alarm timer having therein parametersrelated to the linear and non-linear variables such as those occurringdue to steak thickness and desired degree of doneness, and havingcircuitry adapted to adjust timing accordingly, said timer including analarm, a control circuit for actuating said alarm capable of providingvarying cooking times, a power supply for said control circuit, saidcontrol circuit including a timing circuit adapted to provide a fixedbase time period and an additional variable time period prior toactuating said alarm, a plurality of controls for said variable timeperiod portion of said timing circuit corresponding to said variable insteak-cooking time and corresponding to said parameters, at least one ofsaid controls varying on a nonlinear basis, whereby said alarm time willvary in accordance with required cooking time.
 6. A steak-cooking alarmtimer as set forth in claim 5 and having scales associated with saidcontrols, said scales being marked to accord with the desired respectivesaid parameters.
 7. A steak-cooking alarm timer as set forth in claim 6in which said controls are variable resistors in an RC circuit, and saidscales are marked corresponding to required cooking times for steakthickness and degree of doneness.